Entropy and Information Causality in General Probabilistic Theories (2009)
Barnum, Howard, Barrett, Jonathan, Clark, Lisa Orloff, Leifer, Matthew, Spekkens, Robert, Stepanik, Nicholas, ...
We investigate the concept of entropy in probabilistic theories more general than quantum mechanics, with particular reference to the notion of information causality recently proposed by Pawlowski...
Three Slit Experiments and the Structure of Quantum Theory (2009)
Ududec, Cozmin, Barnum, Howard, Emerson, Joseph
In spite of the interference manifested in the double-slit experiment, quantum theory predicts that a measure of interference defined by Sorkin and involving various outcome probabilities from an...
Information processing in convex operational theories (2009)
Barnum, Howard, Wilce, Alexander
In order to understand the source and extent of the greater-than-classical information processing power of quantum systems, one wants to characterize both classical and quantum mechanics as points in...
Barnum, Howard, Wilce, Alexander
We review some of our recent results (with collaborators) on information processing in an ordered linear spaces framework for probabilistic theories. These include demonstrations that many...
Teleportation in General Probabilistic Theories (2008)
Barnum, Howard, Barrett, Jonathan, Leifer, Matthew, Wilce, Alexander
In a previous paper, we showed that many important quantum information-theoretic phenomena, including the no-cloning and no-broadcasting theorems, are in fact generic in all non-classical...
Nonclassicality without entanglement enables bit commitment (2008)
Barnum, Howard, Dahlsten, Oscar C. O., Leifer, Matthew, Toner, Ben
We investigate the existence of secure bit commitment protocols in the convex framework for probabilistic theories. The framework makes only minimal assumptions, and can be used to formalize quantum...
The Many-Worlds Interpretation of Quantum Mechanics (2008)
call it, following Everett, the “relative state ” interpretation of quantum mechanics. It was rejected by one journal in 1990, primarily on the (I think incorrect) grounds that it was too similar...
Herbert J. Bernstein, Howard Barnum, Nikhil Swamy
Abstract- This paper documents the discovery of a new, better-than-classical quantum algorithm for the depthtwo AND/OR tree problem. We describe the genetic programming system that was constructed...
Howard Barnum, Claude Crepeau, Daniel Gottesman, Adam Smith
Authentication is a well-studied area of classical cryptography: a sender A and a receiver B sharing a classical private key want to exchange a classical message with the guarantee that the message...
A generalized no-broadcasting theorem (2007)
Barnum, Howard, Barrett, Jonathan, Leifer, Matthew, Wilce, Alexander
We prove a generalized version of the no-broadcasting theorem, applicable to essentially \emph{any} nonclassical finite-dimensional probabilistic model satisfying a no-signaling criterion, including...
Entanglement and Subsystems, Entanglement beyond Subsystems, and All That (2007)
Viola, Lorenza, Barnum, Howard
Entanglement plays a pervasive role nowadays throughout quantum information science, and at the same time provides a bridging notion between quantum information science and fields as diverse as...
Generalizing earlier work characterizing the quantum query complexity of computing a function of an unknown classical ``black box'' function drawn from some set of such black box functions, we...
Cloning and Broadcasting in Generic Probabilistic Theories (2006)
Barnum, Howard, Barrett, Jonathan, Leifer, Matthew, Wilce, Alexander
We prove generic versions of the no-cloning and no-broadcasting theorems, applicable to essentially {\em any} non-classical finite-dimensional probabilistic model that satisfies a no-signaling...
In this paper, I propose a project of enlisting quantum information science as a source of task-oriented axioms for use in the investigation of operational theories in a general framework capable of...
Somma, Rolando, Barnum, Howard, Ortiz, Gerardo, Knill, Emanuel
We consider quantum computational models defined via a Lie-algebraic theory. In these models, specified initial states are acted on by Lie-algebraic quantum gates and the expectation values of Lie...
Influence-free states on compound quantum systems (2005)
Barnum, Howard, Fuchs, Christopher A., Renes, Joseph M., Wilce, Alexander
Let Alice and Bob be able to make local quantum measurements and communicate classically. The set of mathematically consistent joint probability assignments (``states'') for such measurements is...
Barnum, Howard, Ortiz, Gerardo, Somma, Rolando, Viola, Lorenza
We define what it means for a state in a convex cone of states on a space of observables to be generalized-entangled relative to a subspace of the observables, in a general ordered linear spaces...
Better bound on the exponent of the radius of the multipartite separable ball (2004)
Gurvits, Leonid, Barnum, Howard
We show that for an m-qubit quantum system, there is a ball of radius asymptotically approaching kappa 2^{-gamma m} in Frobenius norm, centered at the identity matrix, of separable (unentangled)...
Entanglement as an Observer-Dependent Concept: An Application to Quantum Phase Transitions (2004)
Ortiz, Gerardo, Somma, Rolando, Barnum, Howard, Knill, Emanuel, Viola, Lorenza
This paper addresses the following main question: Do we have a theoretical understanding of entanglement applicable to a full variety of physical settings? It is clear that not only the assumption of...
Entanglement beyond subsystems (2004)
Viola, Lorenza, Barnum, Howard, Knill, Emanuel, Ortiz, Gerardo, Somma, Rolando
We present a notion of generalized entanglement which goes beyond the conventional definition based on quantum subsystems. This is accomplished by directly defining entanglement as a property of...
Nature and Measure of Entanglement in Quantum Phase Transitions (2004)
Somma, Rolando, Ortiz, Gerardo, Barnum, Howard, Knill, Emanuel, Viola, Lorenza
Characterizing and quantifying quantum correlations in states of many-particle systems is at the core of a full understanding of phase transitions in matter. In this work, we continue our...
Zurek has derived the quantum probabilities for Schmidt basis states of bipartite quantum systems in pure joint states, from the assumption that they should be not be affected by one party's action...
A subsystem-independent generalization of entanglement (2003)
Barnum, Howard, Knill, Emanuel, Ortiz, Gerardo, Somma, Rolando, Viola, Lorenza
We introduce a generalization of entanglement based on the idea that entanglement is relative to a distinguished subspace of observables rather than a distinguished subsystem decomposition. A pure...
Quantum information science is a source of task-related axioms whose consequences can be explored in general settings encompassing quantum mechanics, classical theory, and more. Quantum states are...
Separable balls around the maximally mixed multipartite quantum states (2003)
Gurvits, Leonid, Barnum, Howard
We show that for an m-partite quantum system, there is a ball of radius 2^{-(m/2-1)} in Frobenius norm, centered at the identity matrix, of separable (unentangled) positive semidefinite matrices....
Quantum query complexity and semi-definite programming (2003)
We reformulate quantum query complexity in terms of inequalities and equations for a set of positive semidefinite matrices. Using the new formulation we: 1. show that the workspace of a quantum...
I consider the tradeoff between the information gained about an initially unknown quantum state, and the disturbance caused to that state by the measurement process. I show that for any distribution...
Authentication of Quantum Messages (2002)
Barnum, Howard, Crepeau, Claude, Gottesman, Daniel, Smith, Adam, Tapp, Alain
Authentication is a well-studied area of classical cryptography: a sender S and a receiver R sharing a classical private key want to exchange a classical message with the guarantee that the message...
Quantum information processing and quantum logic: toward mutual illumination (2002)
Quantum information and computation may serve as a source of useful axioms and ideas for the quantum logic/quantum structures project of characterizing and classifying types of physical theories,...
Largest separable balls around the maximally mixed bipartite quantum state (2002)
Gurvits, Leonid, Barnum, Howard
For finite-dimensional bipartite quantum systems, we find the exact size of the largest balls, in spectral $l_p$ norms for $1 \le p \le \infty$, of separable (unentangled) matrices around the...
A lower bound on the quantum query complexity of read-once functions (2002)
We establish a lower bound of $\Omega{(\sqrt{n})}$ on the bounded-error quantum query complexity of read-once Boolean functions, providing evidence for the conjecture that $\Omega(\sqrt{D(f)})$ is a...
Authentication of quantum messages (2002)
Howard Barnum, Claude Crépeau, Daniel Gottesman, Adam Smith
Authentication is a well-studied area of classical cryptography: a sender A and a receiver B sharing a classical secret key want to exchange a classical message with the guarantee that the message...
August 2000 CSTR-00-013 (2002)
I consider the tradeo# between the information gained about an initially unknown quantum state, and the disturbance caused to that state by the measurement process. I show that for any distribution...
Quantum message authentication codes (2001)
This paper has been withdrawn because of an error in the proof of Lemma 1. Without Lemma 1, the result of the main theorem (with the same proof, but omitting the use of Lemma 1 to extend things to...
On the reversible extraction of classical information from a quantum source (2000)
Barnum, Howard, Hayden, Patrick, Jozsa, Richard, Winter, Andreas
Consider a source E of pure quantum states with von Neumann entropy S. By the quantum source coding theorem, arbitrarily long strings of signals may be encoded asymptotically into S qubits/signal...
On quantum coding for ensembles of mixed states (2000)
Barnum, Howard, Caves, Carlton M., Fuchs, Christopher A., Jozsa, Richard, Schumacher, Benjamin W.
We consider the problem of optimal asymptotically faithful compression for ensembles of mixed quantum states. Although the optimal rate is unknown, we prove upper and lower bounds and describe a...
Quantum circuits for OR and AND of ORs (2000)
Howard Barnum, Herbert J Bernstein, Lee Spector
Abstract. We give the first quantum circuit for computing f(0) OR f(1) more reliably than is classically possible with a single evaluation of the function. OR therefore joins XOR (i.e. parity, f(0)...
A quantum circuit for OR (1999)
Barnum, Howard, Bernstein, Herbert J., Spector, Lee
We give the first quantum circuit for computing $f(0)$ OR $f(1)$ more reliably than is classically possible with a single evaluation of the function. OR therefore joins XOR (i.e. parity, $f(0) \oplus...
Quantum Rate-Distortion Coding (1998)
I introduce rate-distortion theory for quantum coding, and derive a lower bound, involving the coherent information, on the rate at which qubits must be used to encode a quantum source with a given...
Information transmission through a noisy quantum channel (1998)
Barnum, Howard, Nielsen, M. A., Schumacher, Benjamin
Noisy quantum channels may be used in many information-carrying applications. We show that different applications may result in different channel capacities. Upper bounds on several of these...
Quantum capacity is properly defined without encodings,” Phys (1998)
Howard Barnum, John A. Smolin, Barbara M. Terhal
We show that no source encoding is needed in the definition of the capacity of a quantum channel for carrying quantum information. This allows us to use the coherent information maximized over all...
Information-theoretic approach to quantum error correction and reversible measurement (1997)
Nielsen, M. A., Caves, Carlton M., Schumacher, Benjamin, Barnum, Howard
Quantum operations provide a general description of the state changes allowed by quantum mechanics. The reversal of quantum operations is important for quantum error-correcting codes, teleportation,...
Information transmission through a noisy quantum channel (1997)
Barnum, Howard, Nielsen, M. A., Schumacher, Benjamin
Noisy quantum channels may be used in many information carrying applications. We show that different applications may result in different channel capacities. Upper bounds on several of these...
Information-Theoretic Approach to Quantum Error Correction and Reversible Measurement (1997)
M. A. Nielsen, Carlton M. Caves, Benjamin Schumacher, Howard Barnum
Quantum operations provide a general description of the state changes allowed by quantum mechanics. The reversal of quantum operations is important for quantum error-correcting codes, teleportation,...
A General Fidelity Limit for Quantum Channels (1996)
Barnum, Howard, Fuchs, Christopher A., Jozsa, Richard, Schumacher, Benjamin
We derive a general limit on the fidelity of a quantum channel conveying an ensemble of pure states. Unlike previous results, this limit applies to arbitrary coding and decoding schemes, including...
This unpublished 1990 preprint argues that a crucial distinction in discussions of the many-worlds interpretation of quantum mechanics (MWI) is that between versions of the interpretation positing a...
Dieks' Realistic Interpretation of Quantum Mechanics: A Comment (1990)
D. Dieks has proposed a semantical rule which he claims yields a realistic interpretation of the formalism of quantum mechanics without the projection postulate. I argue that his proposal is...
Thesis (M.A.)--University of Kansas, Economics, 1962.
Hospital cost functions for developing countries
Wagstaff, Adam, Barnum, Howard
There is extensive literature on hospital cost functions for industrial countries, but very little literature for developing countries. Yet the issues facing policy-makers in all countries are much...
The interaction of fertility and infant mortality is well established. Lower infant mortality can lead to lower fertility by reducing the need for replacement births. Conversely, birth spacing...
How health insurance affects the delivery of health care in developing countries
Kutzin, Joseph, Barnum, Howard
Financial crisis is a common state of affairs in the government health sector of many developing countries, and an increasing number are considering implementing user charges and insurance programs...